The killing of white supremacist leader David Lynch in California raises questions about the competition among members of hate groups – which occasionally turns violent – and the ways in which they finance their operations.

Police have detained tattoo artist Charles “Boots” Demar, another longtime racist skinhead, as a “person of interest” in the case. He has not been charged with homicide – some associates and family members describe him as a close friend of Mr. Lynch – but he was arrested and placed in the Sacramento County jail when officers found methamphetamine and meth-making equipment in his home.

Lynch was shot and killed early Wednesday morning at his home in Citrus Heights, Calif., about 15 miles north of Sacramento. His girlfriend, five months pregnant with their child, was shot in the leg.

Founded in 1987, American Front “espouses an anti-Semitic, white supremacist ideology and disseminates its message in public events that demonize Jews, immigrants, and other minorities,” according to the Anti-Defamation League (ADL), which researches and tracks hate groups.

“Since the early 1990s, American Front members have been involved with criminal activities, starting with juvenile acts of vandalism and violence against left-wing and anarchist targets,” reports the ADL. “However, more serious criminal incidents did not take long to emerge and the American Front developed a legacy of criminal activity that ranged from brutal hate crimes to acts of terrorism.”

Mark Pitcavage, ADL’s director of investigative research, says of Lynch: “In one sense, his longevity was one of his most noticeable features, as he became an active racist skinhead back in the 1980s, when that subculture was still forming in the US, and stayed in that subculture for more than 20 years.”

“He was, however, not without his enemies or detractors in the white supremacist movement,” Mr. Pitcavage says. “For example, he was sometimes called a snitch for testifying in a trial related to the Kehoe brothers.” (In 2005, white supremacist Chevie Kehoe was convicted and given three life sentences for the kidnapping, torture, and murder of a gun dealer and his family. His younger brother Cheyne Kehoe testified against him. The murders were connected with a pursuit of guns and money.)

The Southern Poverty Law Center (SPLC), which also tracks hate groups, describes Lynch as “a clever and charismatic racist skinhead organizer whose history of racist activism dates back to the late 1980s, when he became the eastern states coordinator for American Front, a nationwide skinhead coalition modeled after Britain’s racist National Front.”

For now, law-enforcement officials are investigating several lines of inquiry as to why anybody would want to kill Lynch, who worked as an asbestos remover when he wasn’t networking with other skinhead and neo-Nazi groups across the United States.

“Lynch was one of the players on the neo-Nazi scene who was noteworthy for his length of time on the playing field,” says Mr. Levin. “He may not have even been the very best, but he had the longevity, organizational skills, a respectable job, and a dose of charisma.”